Coolant circulating system



I Dec. 5, 1944. P. F. BARKER- I COOLANT CIRCULATING SYSTEM Filed Aug. 3,1942 2 Sheets-Sheet 1 PAUL BARKER 8g W H We Dec. 5, 1944. P. F. BARKER2,364,418

COOLANT CIRCULATING SYSTEM Fi'lpd Aug. 5, 1942 2 Sheets-Sheet 2 Q 5 QEmaentor PHI/L F. BARKER Gttomeg are difficult to Patented Dec. 5, 1944COOLAN T CIRCULATIN G SYSTEM Paul F. Barker, Brighton,

Gleason Works, Rochester,

of New York N. Y., assignor to N. Y., a corporation Application August3, 1942, Serial No. 453,366

2 Claims.

The present invention relates to grinding machines and more particularlyto the coolant-circulating systems of such machines.

In most grinding, especially in most gear grinding, it is the practicetoday to wet-grind, that is, to supply a liquid coolant to the grindingwheel and work at their area of contact in order to cool the wheel andthe work and to wash away the bits of metal, which are ground off thework, and the abrasive grits, that are WOI'n off of the wheel, in thegrinding operation. The coolant is usually pumped onto the wheel andwork from a sump or tank mounted in the base of the grinding machine,and after use the coolant flows back to the sump for use again. Sincethe returning liquid is laden with particles of metal and 'abra- I sive,it is necessary to clean the coolant before it is used again, otherwisethe bits of metal and abrasive will be pumped up onto the Work again andmay become wedged between the wheel and work, causing scratching of theWork and rapid wear of the wheel.

Water or a suitable emulsion may beusedas the coolant, but in recentyears it has become more and more the practice to use oil for thispurpose. Where water is employed as the coolant, it is usual to providethe sump or tank with two chambers, a settling chamber and a pumpchamber, constructed in such way that the coolant will have tooverflowfrom the settling chamher into the pump chamber. The settling chamber ismade large enough to allow the particles of metal and abrasive to settleout of the coolant liquid into the bottom of the chamber. In some cases,also, a system of bafiles is employed which the coolant has to return tothe pump chamber. These aid in the removal of the abrasivegrits andmetal particles from the coolant.

Where oil is used as a coolant, however, it has been found that neitherthe settling chamber, nor the baffle system, nor the two combined,operate very satisfactorily. Because of the viscosity of the oil, theparticles tend to remain in suspension and the finer particlesespecially do not settle out but are carried over into the pump chamberwhere they are returned suspended in the coolant to the wheel and thework. It has become the practice, therefore, to filter the cooling oilbefore using it again. The ordinary commercial filters are, however,expensive, and they clean. Moreover, they have to be cleaned quite oftenbecause under the conditions encountered in a grinding operation, theyload up quickly.

The primary object of the present invention is through able conduits toto provide a coolant-circulating system, especially for use where oil isemployed as the cooling medium, which will insure delivery of cleancoolant to the wheel and the work.

Another object of the invention is to provide a filter unit for use in acoolant-circulating system that will be efficient, simple, andinexpensive, and, moreover, that will be easy and cheap to service.

Other objects of the invention will be apparent hereinafter from thespecification and ,from the recital of the appended claims.

In the drawings:

Fig. 1 is the Slide elevation of a standard form of spiral bevel andhypoid pinion grinder on which the coolant-circulating system and filterunit of the present invention is employed;

Fig. 2 is a plan view of the principal parts of the coolant-circulatingsystem, including the filter unit; and

Fig. 3 is a transverse sectional view through these parts.

In the coolant-circulating system of the present invention, the coolantis pumped from the sump through a filter unit and thence through suitthewheel and work, and after use, the coolant flows back into the sumpwhence it is pumped again through the system. The filte-r unit consistssimply of a pail partially filled' With small rhomboidal orlozenge-shaped cast iron pieces or with crushed stone. As the coolant ispumped through the filter unit, the chips and abrasive grits are caughtand removed. The use of crushed stone as the filtering medium ispreferred. In fact, the discovery that such a material may be employedas a filtering medium in the coolant-circulating system of a grindingmachine is one of the features of the present invention, Crushed stonecan be obtained readily almost anywhere and it is so cheap that it canbe thrown away. after use. Cast iron pieces .On the other hand are areimpractical to clean. Moreover, if the quantity of stone used warrantsit, the stone can be cleaned in an incinerator without damage, whereasthe heat required to burn 01f the chips and grits would melt or fusecast iron pieces.

While the invention may be applied to any type of grinding machine, itis shown in the drawings in use on a spiral bevel and hypoid piniongrinder of the type illustrated in the patent of Ernest Wildhaber, No.2,252,743, of August 19, 1941. Grinding ,on this machine is effected bya rotary annular grinding wheel, such as designated at W in Fig. 1, andthe Work piece is a spiral bevel more expensive, and they or hypoidpinion, such as denoted at P in Fig. 1, the side surfaces of whose teethare to be ground by the wheel. A suitable guard I is provided to enclosethe wheel, and coolant is supplied to the wheel and work at the area oftheir engagement through a nozzle 1 l which is suitably mounted in theguard H). The coolant is pumped to the nozzle H from a tank, which isdesignated as a whole at [2, and which is removably mounted in the basel4 of the machine.

The tank is divided into two chambers. One of these chambers, which isdenoted at l5, contains the filter unit. It is square shaped and isformed in one corner of the tank. It is separated from the otherchamber, which is denoted at [6, by the partition walls l1 and 18. Thechamber I6 is L-shaped and forms the sump chamber proper. The coolantfalling from the guard I0, and draining back to the tank, after use,flows into the sump chamber l6 through the rectangular opening in thetop wall of this chamber. The used coolant is conducted to the sumpopening 20 through a suitable conduit (not shown) which may be in theform of piping, or a drain trough, or the like.

The filter unit is mounted in the chamber I5. The filter unit comprisesa pail which has apertures 26 in its bottom and which is partiallyfilled with crushed stone or with metal pieces 21. The pail is flangedat its top and depends through a circular opening formed in the top wall28 of the chamber 15. The flanged rim of the pail seats on thesurrounding part of the top wall 28 of the chamber l5 and the pail isthus suspended in the chamber.

The opening in the top wall 28 is closed by a cover plate 30 which ishinged on the top wall 28 by means of the hinge pin 3|. The cover platemay be clamped down to seal it against leakage by a clamping bar 32 anda clamping screw 33. The clamp bar is pivoted at one end on a pin 34which is mounted in the plate 28 and at its opposite end it is notchedto engage under the head of a pin 35 which is also secured in the plate28. A bail 36 is provided for the pail so that it can be lifted out ofthe chamber l5 to clean or remove the stones 21.

The coolant is pumped from the sump chamber l6 by a pump of any suitableconstruction such as a centrifugal pump shown at 40 in the drawings. Thecoolant is drawn into the pump through the duct 4!. From the pump 40,the coolant is pumped through the piping 42 into a duct 43 that may beformed by an angular piece of sheet metal which is secured to the sidewall l1 and top wall 28 of the chamber 15. The duct 43 communicatesthrough an opening 44 in the top wall 28 with a duct 45 that is formedin the cover plate 30. This duct 45 conveys the oil to the pail 25, andthe pump pressure forces the oil through the filter pieces 21 into thechamber l5 from whence the pressure forces it into the pipe 41. Thispipe is secured in an opening in the top wall 28 of the chamber l5.There are two pipes 48 and 49, respectively, connected to the pipe 41.The pipe 48 communicates with the nozzle II and supplies the coolant tothe area of contact of the wheel and the work. The pipe 49 is anoverflow pipe and preferably conducts coolant to the drain trough orpiping through which the coolant returns to the sump chamber after use.The coolant flowing through the pipe 48 helps wash the grit and chipsdown into the sump and keep the. trough or'conduit clean.

There is a hand operated valve 5| mounted in the pipe 41 to control theflow of liquid between the pipe 41 and the pipe 49. The pump pressure isgreater than that required to force the necessary quantity of coolant tothe area of engagement of the wheel and the work, and the excess liquidflows through the pipe 49 to the sump. Through continued use, the stones21 pick up more and more chips and grits and the interstices between thestones become gradually clogged up so that more and more pressure isrequired to force the dirty oil through these filter pieces. Thus theamount of pressure for carrying the coolant to the point of operationgradually decreases with use of a given charge of the filter unit, sothat it is necessary for the operator from time to time to adjust thevalve 5| to decrease the flow between the pipes 41 and 49 and therebykeep up the necessary pressure in the pipe 48. This is the purpose ofthe valve 5!.

When the filter unit becomes so clogged that it is no longer usable, apail 25 can be removed from the chamber [5 by opening the cover plate30, and a new pail with clean stones can be put in its place. The topwall 53 of the sump chamber I6 is provided with a cleanout opening whichis closed by a hinged cover plate 54. Beneath this cover plate is acircular drain-plate 55. This drain plate has holes in it and issupported by the top-wall of the chamber IS. The cover plate 54 is shownclosed in Fig. 2. When a filter unit is removed from the chamber [5, thecoverplate 54 may be raised and the pail can then be placed on the topof the drain plate, as is the pail 25 in Fig. 3. so that the oilremaining in the pail can drain into the sump and not be wasted.

As already indicated, the filter pieces 21 may be of any suitablematerial, but are preferably crushed stone. The stones used may be of/4" to screening.

It will be noted that in the coolant-circulating system described, thefilter unit is onthe pressure side of the system. This makes forextendedlife of a charge of the filter unit, because the pump pressurewill force the coolant through the filter when a mere gravity feed wouldclog. Thus if the filter unit were so positioned as to filter the dirtyoil flowing back to the sump by gravity from the wheel and work, theuseful life of a given charge of stones would be relatively short forthere would not be sufiicient pressure to force the dirty oil throughthe stones after they began to load up with chips and grit.

While the invention has been described in connection with a particularembodiment thereof and a particular use therefor, it will be understoodthat it is capable of further modification and use. This application isintended to cover any variations, uses, or adaptations of the inventionfollowing, in general, the principles of the invention and includingsuch departures from the present disclosure as come within known orcustomary practice in the art to which the invention pertains and as maybe applied to the essential features hereinbefore set forth and as fallwithin the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. In agrinding machine having a work suport and a grinding wheel, asystem for circulating coolant to the point of engagement of the wheelwith the work comprising an enclosed prising an enclosed sump chambersump, an enclosed filter chamber, an enclosed filter unit in the form ofa pail removably mounted in the filter chamber and having openings inone wall thereof which communicate with the filter chamber so that thecoolant may flow from said unit into the chamber, said filter unit beingof such dimension as to occupy only part of the filter chamber, a pumpfor pumping coolant out of the sump and through the filter unti into thefilter chamber, and piping for conducting the coolant from the filterchamber to the point of engagement of the wheel with the work, and meansfor conducting the used coolant back to the sump for recirculation bythe pump.

2. A coolant circulating system for a grinding machine, particularly fora machine employing oil of relatively high viscosity as a coolant,comfor the coolant, a fully enclosed filter chamber separated from thesump chamber, a filter unit removably mounted in the filter chamber andcomprising a pail partially filled with irregular shaped insolublepieces and having openings in its bottom for passage of the coolanttherethrough, a pump for pumping the coolant from the sump chamber intothe top of said pail, piping for conducting the coolant from the filterchamber to the point of use after the coolant has passed through thefilter unit, and means for conducting the coolant after use directlyback to the sump chamber, said enclosed sump chamber having drainageopenings in its top wall over which a filter pail may be placed, whenremoved from the filter chamber, to permit drainage back into the sumpof the coolant remaining in said pail.

. PAUL F. BARKER.

